### Tonnage Tax System in Shipping Industry

#### Overview
The Tonnage Tax System is a special taxation mechanism adopted by several countries to offer a more stable fiscal environment for shipping companies. Under this system, shipping companies are taxed based on the tonnage (capacity) of their fleet, rather than on their actual income from shipping activities. This method simplifies the tax calculation, reduces administrative burdens, and aims to encourage growth and investment in the national maritime sector.

#### Calculation of Deemed Taxable Income
The taxable income under the tonnage tax regime is not based on actual profits but on a notional income estimated according to the net tonnage of each ship operated by the company. Net tonnage refers to a vessel's total internal volume, minus spaces that are not used for cargo or passengers, expressed in "tons". A crucial aspect of this system is the determination of the notional daily profit per net ton, which forms the base for tax calculations.

#### Notional Daily Profit Rate
In the context of tonnage tax, the notional daily profit per net ton represents an assumed amount of profit that each ton of a ship’s capacity is considered to earn per day. This rate is pivotal because it directly influences the tax liabilities of the shipping companies and thus impacts their financial planning and competitiveness. 

The specified rates for calculating deemed taxable shipping income under the tonnage tax system are structured in a progressive manner based on the ship's capacity. Here is how these rates apply:

1. **For ships with a net tonnage up to 25,000 tons**, the rate set is 40 cents per 10 tons each day. This rate applies to the majority of cargo ships and tankers that typically fall under this size category. For a ship of, say, 10,000 tons, the daily notional income would be calculated as 10,000 / 10 * 0.40 = $400.

2. **For ships exceeding 25,000 tons in net tonnage**, the rate is reduced to a lower bracket of 20 cents per 100 tons each day, recognizing the economies of scale larger ships operate under. For example, a ship of 30,000 tons would have a daily notional income of 30,000 / 100 * 0.20 = $60.

#### Objective and Impact
The differentiation in rates between smaller and larger vessels takes into account the economic principle of economies of scale, where larger ships generally have lower operational costs per ton compared to smaller vessels. This tax structure ensures that the tax burden is equitably distributed relative to the size and earning capacity of the ship.

Such a fiscal strategy not only stabilizes the tax obligations of shipping firms but also makes financial outcomes more predictable. This predictability is crucial for long-term business planning and investment in new ships or retrofitting existing ones to meet newer environmental regulations. Additionally, it supports the global competitiveness of carriers registered under a nation’s flag by aligning tax burdens with international standards.

#### Conclusion
The tonnage tax system represents a significant departure from traditional corporate income taxes and is tailored to address the unique characteristics of maritime transport. By linking tax liability directly to the ship's capacity rather than its earnings, the system provides a straightforward, predictable, and equitable framework for taxing maritime commercial operations. The specific rates and thresholds, such as the 40 cents per 10 tons and 20 cents per 100 tons, reflect an approach designed to accommodate different scales of operation within the industry, supporting both smaller enterprises and large multinational conglomerates alike.